Autostereoscopic reproduction system for 3d displays

ABSTRACT

What is described is a position-adaptive autostereoscopic 3-D reproduction system for generating 3-D images or scenes, having a flat image screen ( 1 ) with colour subpixels (R, G, B) lying side by side, a raster screen ( 2 ), a coding unit ( 6, 9 ) and a processor unit ( 3 ) for generating perspective images. According to the invention, the coding unit ( 6, 9 ) is controllable and the raster screen ( 2 ) is dimensioned and arranged such that first and second mutually interlaced subpixel strips appear on the image screen ( 1 ) and from these, first and second image strips are generated, which appear to the two eyes of an observer to be disjoint for a defined viewing region in front of the image screen ( 1 ), whereby a constant sequence of colours of the subpixels is maintained in the first (second) subpixel strips.

The invention relates to an autostereoscopic reproduction systemaccording to the precharacterising portion of claim 1.

Compared with 2-dimensional, conventional representations, a3-dimensional representation comes closer to natural visual perception.The degree of naturalness can be further enhanced by anautostereoscopic, position-adaptive representation. For this purpose,various autostereoscopic imaging methods have been developed which useeither barrier masks, lenticular raster masks or prismatic raster masksfor optical separation of right and left imaging directions for whichdifferent subpixel adaptations are required. Creating theserepresentations required for 3-D animations, interactive games andvector-format films in real time on PCs has so far not beensatisfactorily achievable, although stereoscopic films and projectiontechniques have been in use for years. These use, for instance,polarised light (horizontal/vertical or circular) in order to separatethe left and right images. The technical advance of LCD technology madeit possible to control the opacity of crystals electronically. This madepossible the development of shutter technology whereby the right andleft lens of a pair of spectacles alternately become opaquesynchronously at half the image frequency and synchronously therewith,the right and left images appear sequentially on the image screen. Thismethod is also used by autostereoscopic shutter monitors.

For several years, autostereoscopic reproduction systems with TFTdisplays have also been in use, which produce right and left images onan image screen horizontally multiplexed and create spatially separatedprojection directions by means of raster screens (DE-A-41 14 023, U.S.Pat. No. 6,307,585, DE-A-198 27 590, DE 198 22 342 and van Berkel in“Image for 3D-LCD, Philips Research Laboratories, UK, SPIE vol. 3639,1999, pp. 84-91). Reproduction systems of this type can also be designedposition-adaptive using head-trackers (U.S. Pat. No. 6,307,585 andAndiel, Hentschke et al. in “Eye-tracking for autostereoscopic displaysusing web cams”, SPIE vol. 4660, 2002, pp. ₂₀₀-206).

In a known reproduction system of the aforementioned type (PAM, EP 0 836332 A2), the individual image pixels of an image screen formed fromthree subpixels R, G and B are controlled by means of a coding unit lineby line with right and left image strip signals such that in every linealternately right and left subpixel strips are formed, which serve tocreate image strips assigned to left and right, known in the followingas horizontal “multiplexing” or “interlacing” of the left and rightimages. Furthermore, a raster screen in the form of a prismatic orlenticular raster screen is positioned in front of the image screen suchthat it brings together the right and left image strips for a definedviewing region in front of the image screen comprising, respectively, aright and a left viewing direction into the right and left imagesrequired for 3-D images. For reliable separation of the right and leftimages, those subpixels are set-dark which fall within empty regions oroverlap regions, whereby empty regions contain subpixels not visiblefrom both viewing directions and overlap regions contain subpixelsvisible from both viewing directions simultaneously. Furthermore,control of the subpixels visible only from the right viewing directionor only from the left viewing direction is performed such that eachright or left subpixel strip has exactly three different-colouredsubpixels side by side.

In this method of control, the sequence of the individual subpixels inthe horizontal—or line—direction depends above all on the respectiveobserver position that is notified to the coding unit, for instance, bymeans of an autostereoscopic position detector such as a head tracker oreye tracker. It could therefore occur that the sequence of subpixels ina selected subpixel strip is, for instance, RGB and in a subpixel striplying adjacent to the left or right of it is, for instance, GBR or BRG.From this arises the as yet unsolved problem that colour faults may bethereby caused that at the borders of two subpixel strips, the samecolours appear, for instance, if a subpixel strip BRG follows a subpixelstrip RGB.

Following from this, the invention is based on the technical problem ofimproving the 3-D reproduction system of the aforementioned type suchthat colour faults of the type mentioned are avoided. Nevertheless, thereproduction system should be able to be operated in real time and witha resolution which at least approaches photographic quality.

This aim is fulfilled by the characterising features of claim 1.

The invention has the advantage that it enables reliable separation ofright and left images even if the spatially multiplexed subpixelrepresentation is made adaptive with the aid of position detectors. Theraster screens used to separate the right and left images may be simplelenticular or barrier raster screens that are mounted at a smalldistance in front of the image screen concerned. The loss of resolutionbrought about in the horizontal direction by the spatial separation maybe largely recovered by means of a special recoding device.

Further advantageous features of the invention are contained in thesubclaims.

The invention will now be described in greater detail, based on exampleswith the aid of the drawings, in which:

FIG. 1 shows a schematic representation of a 3-D reproduction systemaccording to the invention;

FIGS. 2 and 3 show different representations of optical ray paths forthe right and left eye on use of a lenticular raster screen providedwith relatively broad cylindrical lenses, for a portion of a horizontalsubpixel line of an image screen of the reproduction system of FIG. 1;

FIG. 4 shows a representation according to FIG. 2 on use of a lentictlarraster screen with relatively narrow cylindrical lenses;

FIGS. 5 and 6 show representations according to FIGS. 2 and 4 on use ofa barrier raster screen with larger or smaller raster divisions in thereproduction system of FIG. 1;

FIG. 7 shows copying procedures of compressed right and left images ontothe subpixels of an image screen in interlaced form;

FIG. 8 shows the allocation of subpixel strips dependent upon theposition of an observer in front of the image screen;

FIG. 9 shows a representation of an optical ray path corresponding toFIG. 2, but in conjunction with a plurality of subpixel lines of animage screen of a reproduction system of FIG. 1 arranged verticallyabove one another; and

FIG. 10 shows in a representation corresponding to FIG. 9, a furtherembodiment of the invention.

FIGS. 1 and 2 show in schematic form a reproduction system according tothe invention for 3-D representations which may contain images orscenes. The reproduction system comprises, in particular, a flat imagescreen 1 (TFT or plasma screen) in front of which is arranged a rasterscreen 2, designed here as a lenticular raster screen. According to FIG.2, the image screen 1 comprises a plurality of adjacently positioned,for instance, respectively 1024 to 1920 image pixels each composed ofthree coloured subpixels in the colours red (═R), green (=G) and blue(=B) lying side by side in a plurality of, for instance 768 to 1200(horizontal) lines. Within each image pixel, the sequence of subpixelsis always the same, e.g. RGB.

A processor unit 3 serves to generate 3-D representations, saidprocessor unit including, for instance, a graphics card provided with astore to which the electrical signals of images, scenes or similar arefed in real time from a camera or similar. Alternatively, these signalsmay also come from a mass storage device and be continuously updated.The images may also be stored on the card in another form, for instance,in point form.

Right and left image signals are generated by the processor unit 3 inthe original size and in pixel form for right and left images 4 and 5schematically indicated in FIG. 1 by rectangles and respectively stored,for instance, in right and left stores. These image signals are then fedto a block 6 and each compressed, relative to the image screen width,for instance, to a third of their original width and, in particular, inthe same proportion as later they are expanded again by the rasterscreen 2. By this means, image signals for narrow right and left images7 and 8, indicated by further rectangles, are obtained. Furthermore, theimage signals are subjected in block 6 to further treatment explainedbelow and denoted for short here as HR filtering.

The signals of the compressed images 7 and 8 are fed to a further block9 where they are split into signals for right and left image strips 10and 11. Calculation of the image strip signals is preferably undertakenadaptively, i.e. dependent upon the position of an observer in front ofthe image screen, for which purpose, in particular, the respective startposition of the image strips 10 and 11 on the image screen followingeach movement have to be determined anew and precisely. The image stripsignals are also interlaced or multiplexed in the block 9 such that theassociated image strips 10, 11 alternate as per FIG. 1 in the linedirection, whilst in the column direction (vertically), they are, forinstance, continuous. The signals representing the right and left imagestrips 10, 11 are finally fed via a typical interface 12 to the monitoror similar provided with the image screen 1.

In order that calculation of the image strip signals may be madeadaptively, for instance, an eye tracker 14 is assigned to the observer,its signals being fed to the processor unit 3 and the device containingthe blocks 6 and 9, denoted overall below as the coding unit.Furthermore, the reproduction system of FIG. 1 may be provided in theusual manner with a 3-D mouse 15, an input control system 16, a 3-Dlibrary 17 and possibly an adjusting device 18 for person-specificadjustments.

FIG. 2 shows schematically in the uppermost portion, some subpixels ofthe flat image screen 1 of FIG. 1 identified with the reference symbolsR (=red), G (=green) and B (=blue), whereby respectively three suchsubpixels R, G, B and from left to right in each image pixel always havethe same sequence, e.g. RGB-RGB, etc. FIG. 2 also shows that arranged infront of the subpixels representing the image screen 1 is a lenticularraster screen 20 shown in cross-section which has a glass pane 21 and aplurality of adjacent vertically extending cylindrical lenses (e.g. afew hundred) which, for instance, are mounted on the broad side of theglass pane 21 facing towards the observer, of which however only twocylindrical lenses 22 a and 22 b are shown in FIG. 2. Finally, FIG. 2shows schematically the optical ray path, starting from a right and aleft eye 23, 24 of an observer.

According to the invention, the lenticular raster screen 20 isdimensioned and arranged such that at least the right and left imagestrips generated in a selected region of the image screen 1 by thesubpixels R, G and B appear to the observer to be overlap-free anddisjoint and the sequence of colours on the transition from a right(left) subpixel strip to the respective previous or subsequent right.(left) subpixel strip is always continued consistently. This isapparent, for instance, from FIG. 2. Here right and left subpixel strips25 a, 25 b and 26 a, 26 b are alternately formed, each comprising sixsubpixels R, G and B, whereby the right subpixel strip 25 a starts atthe left with a green subpixel and ends on the right with a redsubpixel, whilst the next right subpixel strip 25 b also begins on theleft with a green subpixel and ends on the right with a red subpixel,such that—seen over the two pixel strips—the colour sequence G, B, R isalways maintained from left to right continuously. Accordingly, for theleft subpixel strips 26 a, 26 b, the colour sequence GBR, GBR is alsoproduced throughout, seen from left to right.

When the number of adjacent subpixels in both the right and the leftsubpixel strips 25, 26 in FIG. 2 corresponds to a whole-number multipleof the colour number or a whole-number multiple of a pixel width and thepixel strips 25, 26 adjoin each other without intermediate spaces, thenthe right (left) subpixel strips 25, 26 are automatically separated fromeach other such that the intermediate spaces or visual jumps between onelateral end (e.g. 26 c in FIG. 2) of a right (left) subpixel strip and afacing lateral end (e.g. 26 d) in FIG. 2 of a right (left) subpixelstrip leading and/or following in the line direction exactly correspondsto a whole number multiple of an image pixel (or of the existing numberof pixel colours). It might, however, be regarded as disadvantageousherein that the right and left subpixel strips each border each otherdirectly, which on imprecise positioning of the raster screen 20 and onslight movements of the observer could lead to image faults. It istherefore proposed in a further development of the invention to providefurther subpixels R, G and B between the subpixel strips 25, 26. This ismade clear in FIG. 2 in that between the subpixel strips 25 a and 26 aor 26 a and 25 b or 25 b and 26 b, three further subpixels 27 a, 27 b or27 c are arranged in each case. These further subpixels 27 serve, on theone hand, to improve the spatial separation of the subpixel strips 25,26 while, on the other hand, permitting limited head movements by theobserver, as described in greater detail below, but without causingimage faults. The latter applies in particular if the number of furthersubpixels 27 corresponds, according to the invention, to a whole numbermultiple of the pixel width or of the available pixel colours (herethree). In this event, it is also unimportant how many subpixels arepresent per subpixel strip 25, 26. If each subpixel strip 25, 26 were tocontain, for instance, seven subpixels R, G and B side by side, then,for instance, the strip 25 a would have from left to right the coloursequence GBRGBRG and the subpixel strip 25 b would therefore have thecolour sequence BRGBRGB in unbroken continuation.

FIG. 2 also shows that the coding unit 6, 9 is controllable and theraster screen 20 dimensioned and arranged such that at least those leftand right image strips, e.g. 28 and 29, which are generated in aselected region of the image screen 1 (e.g. in its left half) are seenoverlap-free by the observer. It is clear that in FIG. 2 the right imagestrips 28 are generated by the right subpixel strips 25 and the leftimage strips 29 are generated by the left subpixel strips 26, and allthe right or left image strips 28 and 29, of which only two are shown inFIG. 2, are brought together by the raster screen 20 to a right and leftimage for the right and left eye 23, 24, permitting spatial perception,whereby by means of the raster screen 20, stretching of the imagescorresponding to the prior compression in the block 6 (FIG. 1) takesplace.

FIG. 3 shows a simplified representation substantially corresponding tothat in FIG. 2 except for the missing subpixels, although with two rightimage strips 28 a, 28 b and two left image strips 29 a and 29 bgenerated by the subpixel strips, which are merged together by thelenticular raster screen 20 to right and left images. From FIG. 3, aboveall, the above described separations between the ends of the right andleft image strips 28 a, 28 b and 29 a, 29 b facing towards each otherare clearly recognisable as visual jumps 30, 31, each having the widthof a whole number multiple of one pixel width (here=3 subpixel widths).

The embodiment according to FIG. 4 differs from that of FIGS. 2 and 3 inthat a lenticular raster screen 33 which here is provided on the sidefacing towards the image screen with cylindrical lenses 34, has a lenswidth or a pitch separation which substantially corresponds to the widthof two subpixels R, G or B. In this embodiment, the coding unit 6, 9 isagain controlled in such a manner, and the raster screen 33 dimensionedand arranged in such a manner, that at least the right and left imagestrips generated in a selected region of the image screen appearoverlap-free to an observer and a constant sequence of colours of thesubpixels in right (left) subpixel strips 35 a, b, c or 36 a, b, c isobtained. As distinct from FIGS. 2 and 3, each subpixel strip 35, 36 hasthe width of one subpixel, and the interlacing is such that the rightpixel strip 35 is separated and spaced from a left subpixel strip 36.Therefore associated image strips 37 and 38 which are grouped togetherby the lenticular raster screen 33, respectively to a right image and aleft image, appear to be correspondingly interlaced and multiplexed.

A protective foil 39 (FIG. 2) or 40 (FIG. 4) may be arranged between theraster screens 20 and 33 and the image screen 1.

In contrast to FIGS. 2 and 3, observation of the spatial representationson use of the raster screen 33 is only fault-free when the observerassumes a substantially rigid position relative to the image screen 1,predetermined by the position and form of the raster screen 33.

In order to avoid this fixed arrangement, which is not always desirable,it would be possible to arrange the raster screen 33 movable relative tothe image screen 1 in the direction of arrows v and/or w, in order bythis means to be able to follow any head movements by the observer.

FIGS. 5 and 6 show embodiments according to the invention of a 3-Dreproduction system corresponding to FIGS. 2, 3 and 4, on use of araster screen 41 or 42 in the form of a barrier raster screen which hasalternate transparent (vertically arranged) strips or slits 43 (FIG. 5)or 44 (FIG. 6) and arranged between these, opaque barrier strips 45(FIG. 5) or 46 (FIG. 6), shown black.

With regard to the optical ray path, substantially the same applies forthe embodiment according to FIG. 5 as for the ray path according toFIGS. 2 and 3. Each transparent strip 43 has a width here whichcorresponds to the width of three subpixels. The raster screen 41 isdimensioned and arranged in front of the image screen 1 such that eachof the eyes 23, 24 of the observer sees image strips 47, 48, thesubpixel strips 49, 50 are generated with a width of three subpixels,and that between these subpixel strips 49, 50, in each case, lie furtherinvisible subpixels 51, 52 which are covered by the barrier strips 45.These further subpixels 51, 52 together have a width corresponding to awhole number multiple of one image pixel such that overall, continuouscolour transitions are produced.

The control of the subpixels not shown in FIG. 5 takes place similarlyto FIGS. 2 and 3, such that the right and left subpixel strips 49, 50alternate. Limited lateral movements of the observer in the direction ofan arrow 53 result in an opposing displacement of the subpixels visibleto the observer in the direction of an arrow 54. The coding unit 6, 9controlled by the eye tracker 14 or similar is arranged such that itautomatically takes account of these changes and, according to thepicture, dependent upon the momentary position of the observer, alwayscontrols those subpixels that are currently visible through thetransparent strips 43.

For the embodiment according to FIG. 6, according to the invention,substantially the same ray path is provided as in the embodimentaccording to FIG. 4. The raster screen 42 has a pitch substantiallycorresponding to the width of two subpixels and each transparent slit 44has approximately the width of a subpixel. Similarly to FIG. 4, theraster screen 42 is therefore dimensioned and arranged such that thesubpixels R, G and B alternately generate right and left overlap-freeimage strips 55, 56 for the right or left eye 23, 34. In contrast toFIG. 5, a fault-free image only results if either the observer assumes apredetermined position in front of the image screen 1 or the rasterscreen 42 is arranged displaceable, in similar manner to FIG. 4,relative to the image screen.

FIGS. 7 and 8 show in schematic form, the control according to theinvention of the subpixels on use of the embodiment according to FIGS. 2and 3. In order to be able to generate fault-free and largely loss-freeright and left images, even given head movements of the observer, thesubpixels (in each case, three subpixels R, G and B) lying in theintermediate spaces between adjacent subpixel strips serve as reservesfor image information. This should be understood to mean that thesesubpixels, which are invisible from the assigned viewing angles shown,for instance, in FIG. 2, are controlled using image signals which alsocorrespond to the last subpixels of the previous or subsequent subpixelstrip.

In FIG. 7, by way of example, in the upper section, a plurality of imagepoints and in the lower section a plurality of subpixels of the imagescreen 1 are indicated, whereby the image points are numbered 64 to 78for a right-hand compressed image and 83 to 100 for a left-handcompressed image. Contrasted with this, the subpixels for an associatedline of the image screen 1 are numbered continuously from 1 to 37.According to the above description, each pixel strip contains 6 visiblesubpixels, followed by three invisible subpixels. This means that inFIG. 7, for instance, at a particular observation angle, the subpixels 1to 6 and 19 to 24 each comprise a right subpixel strip (═SPS.R in FIG.7) and the subpixels 7 to 9 and 25 to 27 form invisible reserve subpixelstrips adjacent thereto. The subpixels 10 to 15 and 28 to 33 accordinglyform a left subpixel strip (SPS.L in FIG. 7) and the remaining subpixels16 to 18 and 34 to 36 each comprise an invisible reserve subpixel strip.As is indicated schematically by arrows, the visible subpixels 1 to 6and 19 to 24 are controlled with the information from the image points64 to 69 or 70 to 75. Simultaneously, the information from the imagepoints 70 to 72 is also copied into the invisible subpixels 7 to 9 andthe information from the image points 76 to 78 is also copied into theinvisible pixels 25 to 27. Similar copying procedures are carried outfor the left-hand images, as FIG. 7 shows clearly.

The described method of additional copying of particular image pointsinto the invisible subpixels 7 to 9 and 25 to 27 has the consequencethat in the event that the observer moves his head by exactly one pixelwidth and therefore now sees, for instance, the subpixels 2 to 7 and 20to 25, he receives the information from the image points 65 to 70 and 71to 76. On further displacement by one subpixel, the observer sees, forinstance, the subpixels 3 to 8 and 21 to 26 and thereby receives theinformation of the image points 66 to 71 or 72 to 77. Similarly for theinformation fed to the left eye and for movements to the left ormovements perpendicular to the image screen. What is important in thiscontext is that in the example the observer receives, for instance, theinformation from the image points 70 to 75, 71 to 76, 72 to 77, etc.continuously and without any colour jump and therefore, in the example,head movements of up to three subpixels to one side or the other can becompensated for without difficulty and without any loss of quality. Thisalso brings both the advantages that errors that can arise due to araster screen not arranged precisely parallel to the image screen can becorrected, and also that at the end of a subpixel strip, only partiallyvisible subpixels in subsequent or previous subpixel strips arecompleted to form one whole subpixel. It is thereby achieved that nopicture and colour information is lost.

Furthermore, head movements by the observer are suitably constantlynotified via the eye tracker 14 or similar to the processor unit 3 andthe coding unit 6, 9, in order to carry out new calculations immediatelyon larger movements, and to recalculate the image signals for therespective observer position, as explained below. By this means,dependent upon the separation of the observer from the image screen 1and different pitch separations and pitch separations deviating fromeven numbers, i.e., for instance pitch separations that correspond to anon-integer multiple of a subpixel and then have to be quantised. If,for instance, for some arbitrary observer position, the pitch 9.2results, then the calculations are initially carried out on the basis ofthe whole number pitch value 9.0 until the ignored remainder after thedecimal point approximates in total to one subpixel. Then calculationcontinues once with a pitch of 10 subpixels etc., such that on averageover the whole screen width, the required pitch of 9.2 always results.By use of fast computers, all these computations including thecalculations necessary for the copying procedures can be carried out inreal time.

The position-adaptive, high-resolution autostereoscopic reproductionsystem PARSC of the present invention is a further development of theknown position-adaptive autostereoscopic monitors PAM (U.S. Pat. No.6,307,585). Compared with this system, the present invention improvesflexibility, real-time capability and resolution. Flexibility isimproved, for instance, thereby that on initialization of the codingunit 6, 9, unique statistical information is transmitted about how theright and left images are generated and interlaced, i.e. how thesubpixels should be horizontally multiplexed, as explained below.

On use of the described reproduction system, according to the invention,the following system operation settings may be provided, which may beswitched on or off and used individually or in combination:

(S1) Undersampled interlace,

(S2) Compression and expansion filtering,

(S3) Barrier interlace,

(S4) Position adaptation,

(S5) Lenticular raster interlace,

(S6) High-resolution filtering.

These six basic settings will now be described in greater detail.

(S1): Interlace with undersampling means that, from the right and leftimages, it is always only those pixels or subpixels that will be pickedout strip-by-strip, which are arranged at the positions of therespective subpixels or the respective generated image strips that arebeing driven on the image screen. These picked-out strips are thenrepresented on the screen spatially multiplexed. This means that theunused strips of both images do not appear and can therefore cause“aliasing” errors, which arise due to information being in the unusedstrips and therefore becoming lost. When, for instance, a vertical lineis situated in such an unused strip of a partial image, it is no longervisible in the reproduced image. Under certain circumstances, however,it could reappear in an adaptive system if the observer moves his headto the side. Such phenomena are also known as Moiré effects. They alwaysarise with undersampling and they are undesirable. An advantage ofundersampled interlacing, however, consists therein that it can becarried out particularly simply and rapidly with common graphics cardsin that, for instance, a right and a left image store are used and theright and left image strips are realised with simple switches. Thismeans that all the required control operations can be carried out inreal time.

(S2): The (S2) version avoids aliasing errors but makes the image lesssharp horizontally due to horizontal low-pass filtering. This filteringproduces the effect that, for instance, vertical lines only one pixelwide are broadened. This operation may be carried out as low-passcompression filtering such that the images are initially reducedhorizontally to the proportion required for the interlacing, forinstance one third. The subpixels required for the interlacing may thenbe taken directly from both compressed images and copied onto the imagescreen. However, the compressed images may also be expanded to theoriginal breadth by means of a filter and then interlaced in accordancewith (S1). An advantage of this is that all the information from theimages is used. It is compressed and thus allocated to narrower strips,such that the original image strips may, for instance, appear only halfas wide. Therefore, contrasted with the advantage of a continuous imagefrom which no information is lost, is the disadvantage of reducedsharpness.

Suitable coefficients for a low-pass filter are, for instance, asfollows:C1_(TP)(I)=(3−|i|)/9 for i=−2 to +2.  (1

Somewhat more favourable is the following cosine filter:C _(TP)2(i)=A·cos²(π·i/6) for i=−2 to +2 and  (2)

where$A^{- 1} = {\sum\limits_{i = {- 2}}^{+ 2}{\cos^{2}( \frac{\Pi \cdot {\mathbb{i}}}{6} )}}$

If PO(f,i) are the colour pixels of a line of the right-hand orleft-hand original image in the i^(th) column with the individual colourvalues R_(o)(i)=P_(o)(0,i), G_(o)(i)=P_(o)(1,i) and B_(o)(i)=P_(o)(2,i).The compression filtering can then be carried out pixel-by-pixel asfollows:

(3) For i=0 to N_(S)/3 for the column number N_(S) of the originalimage:${P_{S}( {f,i} )} = {\sum\limits_{\mu = {- 2}}^{+ 2}{{C_{TP}(\mu)} \cdot {{Po}( {f,{{3i} - \mu}} )}}}$

If the interlace is to be undertaken according to (S1), the low-passfiltration may be carried out without

(4) compression is carried out for i=1 to N_(S):${P_{F}( {f,i} )} = {\sum\limits_{\mu = {- 2}}^{+ 2}{{C_{TP}(\mu)} \cdot {P_{o}( {f,{i - \mu}} )}}}$

From the compressed image, using the filter coefficientsC_(F)(i)=C_(TP)(i)/A=cos²(π·i/6), the converse expansion filtration maybe undertaken, which leads to a low-pass filtered image with the pixelsP_(TP)′ (f,i). Starting from pixel values set to zero P_(TP)′(f, i)=0,the following operation takes place:P _(TP)′(f,3i+k)=P _(TP)′(f,3i+k)+C _(F)(k)P _(F)(f,i), for k=−2 to +2and i=1 to N_(S)/3.  (5)

Any required setting to zero or enhancement at the edge region will notbe considered in detail here.

(S3): Barrier interlacing has previously been briefly described on thebasis of FIGS. 5 and 6.

By means of vertical slits 43, 44 of the barrier raster screen 41, 42,disjoint strips are made visible on the image screen for the right andleft eyes 23, 24. Those subpixels which cover the i^(th) visible stripon the image screen are filled with the right or left pixel values ofthe i-pixel of the right or left compressed image. A slit in the barrierraster screen is approximately as wide as three subpixels R, G, B orsimilar (FIG. 5) or as one subpixel (FIG. 6).

In order to obtain the subpixel numbers and colours on the image screenwhich belong to the right or left visible strips, the precise startingpositions of these strips are calculated. According to the ray paths inFIGS. 2 and 7 and in accordance with FIG. 8, for instance, the firstright-hand strip begins at the position startR and the left-hand stripbegins at startL. The ith strip then begins displaced to the right byi·scpitch, that is the i^(th) multiple of the image screen pitch. IfKr_(SPB)(i) and Kl_(SPB)(i) are the subpixel numbers on the imagescreen, starting at 0, and spsize is the width of one subpixel, then thei^(th) right and left strips begin with the following numbers:Kr _(SPB)(i)=int{(startr+i·scpitch)/spsize}  (6)Kl _(SPB)(i)=int{(startl+i·scpitch)/spsize}.  (7)

Here, int{ } is the integer function which expresses the whole-numberportion of the rational number. The i^(th) right-hand strip thencomprises Kl_(SPB)(i)−Kr_(SPB)(i) subpixels. The values R_(Fr)(i),G_(Fr)(i), B_(Fr)(i) of the ith pixel of the right-hand compressed imageis copied in colour-true manner onto these subpixels. A similarprocedure is followed for the left-hand strip.

As a rule, the colours of the subpixels of a pixel have the sequence redR(2), green G(3), blue B(4). From the number of the subpixel on theimage screen, its colour is obtained via the module-3 function:f _(r)(i)={Kr _(SPB)(i)}mod(3)={Kr _(SPB)(i)}−3·int{Kr _(SPB)(i)/3}  (8)

Here, f=0 stands for R, f=1 stands for G and f=2 stands for B. With afixed interlace according to (S3) of this type, there are as a rulethree fixed positions from which the 3-D vision is satisfactory. Theinterlace operation may, however, be altered so fast that rapidadaptation to changing observer positions is possible. For an adaptivesolution of this type, however, the head tracker or eye tracker 14 isneeded (FIG. 1).

(S4): Position adaptation serves the aforementioned purpose of alwaysfinding on the image screen 1 exactly the correct subpixels belonging tothe images, even if the observer makes sudden movements. This positionadaptation will now be described, by way of example, based on FIGS. 7and 8 in which the abbreviations used below are shown, in addition tothe reference symbols also used in FIG. 2. The arrow heads point toparticular positions on the image screen 1. In the coding unit 6, 9, asthe indication “Start” signifies, the precise start positions arecalculated, from where assignment to the individual subpixels starts.Depending upon the position of the observer, the arrow head may wanderfrom “Start” to the right or the left. If the arrow jumps from onesubpixel to an adjacent subpixel, then as described below (see also FIG.7), a corresponding altered assignment of the subpixels to the subpixelstrips or the image strips produced by them takes place.

The position of the observer is identified with the vector OP (observerposition) or with OP(x), OP(y), OP(z). Most TFT image screens startimage build-up and storage at the bottom left corner. The origin of therelative coordinate system is therefore placed in the bottom left cornerof the image screen. The x-direction is the horizontal direction towardsthe right, the y-direction is upwards on the image screen and thez-direction is the direction perpendicular to the image screen runningforwards. The separation of the observer from the image screen is thenidentical to OP(z). For the interlacing of is the images, it issufficient to know the average positions of the eyes and for the idealseparation of the raster mask in front of the image screen, apart fromthe standard position OP0, the eye separation of the observer is also ofinterest: EyeD=|Eyer−Eyel|. The standard or starting coordinates of theobserver are identified as OP(x0), OP(y0), OP(z0). The most favourableseparation of the raster mask from the image screen RSD is found fromthe raster mask pitch rmpitch:RSD=rmpitch·OP(z0)/(2·EyeD).  (9)

This separation remains constant with continuous position adaptation.From the observer position, the mask pitch increases slightly as far asthe image screen and gives the image screen pitch scpitch (screenpitch).The variable image screen pitch is thenscpitch=rmpitch·{1+RSD/OP(z)}.  

The start position of the first visible right-hand strip on the imagescreen is then also dependent upon the observer position:startr′=K0·scpitch−{OP(x)+EyeD/2}·RSD/OP(z), or for the left eye  (11)startl′=K0·scpitch−{OP(x)−EyeD/2}·RSD/OP(z).  (12)

K0 is meant as the smallest whole number for which startr is positive,in order to avoid negative subpixel positions.

In order to ensure sufficient separation between right andleft—including in a defined observer position—the invisible strips (e.g.27 in FIG. 3) are provided between the visible strips (e.g. 25 and 26 inFIG. 2). In these strips 27, the representation remains free. A flexibleallocation to right or left is, explained below, dependent upon amovement prediction for the observer. A precondition of this is,initially, a mean distribution of the unusable strips, i.e. theinterlacing is oriented towards a mean eye position, whereby the changein the projected separations is not taken into account. From this, themean start position is found:start=K0·scpitch−OP(x)·RSD/OP(z)  (15)

For the i^(th) strip, starting at i=0, the following numbers of thestrip start subpixels are found:KrSPStart(i)=int{(start−scpitch/4+i·scpitch)spsize}  (16)KlSPStart(i)=int{(start+scpitch/4+i·scpitch)/spsize).  (17)

For adaptive calculation of the starting subpixel positions of theinterlaced strips, for each new frame two variables are needed and thesemust be updated up to 100 times per second. If a maximum permissiblevalue is set for these two variables, the required accuracy may beadapted dependent upon the subpixel width. It is apparent thatquantising of the values from “start” to 8 bit=1 byte and for “scpitch”to 16 bit=2 bytes is sufficient. This implies a minimum update data flowof approximately 300 byte/s.

The position adaptation described may be applied on use both of thelenticular raster screen 21, 33 (FIGS. 2 and 4) as well as the barrierraster screen 41, 42 (FIGS. 5 and 6).

(S5): Interlacing on use of the lenticular raster screens 21 and 33(FIGS. 2 and 4) is illustrated schematically in FIG. 7. The upper linerepresents the already compressed right and left images.

The optical ray path on use of a lenticular raster screen is shown inFIGS. 2 to 4. A comparison with the barrier raster screen (FIGS. 5 and6) shows that similar right and left strips and invisible regions areformed, but continuous right and left images without stripes that aredisturbing to the eyes are formed. Nor is brightness absorbed anylonger. In order to determine the start positions for the subpixels ofthe right and left strips on the image screen, the same algorithm may beused according to the formulae (15) and (16). In order to achieve agreater horizontal resolution, the individual subpixels are copied fromthe compressed images into the strips provided without the sequence ofthe subpixels within a strip being altered. The colour-true interlacedcopying of the compressed images in strip regions makes necessaryadditional calculation of the assigned starting subpixels in thecompressed image to the respective starting subpixels in the right andleft strips on the image screen. The lenticular profile of the rasterscreen is calculated here such that the image continues in the followinglens in the subpixel colour with which the first ends. Should a sightchange occur, directly between two subpixels, the following lens beginswith the follow-on colour, i.e. after R comes G, after G comes B, afterB comes R. This allocation is ensured by the following algorithm. Thefirst subpixel that can be used in the compressed right-hand image isthe colour subpixel in the first pixel which has the colour of thestarting pixel of the first right-hand strip on the image screen:F _(r0) ={Kr _(SPStart)(0)}mod(3), with f=0 for R, f=1 for G and f=2 forB.  (18)

The left-hand first strip begins with the colourf ₁₀=(Kl _(SPStart)(0)}mod(3)  (19)

These colour pixels are therefore taken from the first pixels of thecompressed images. The first pixels generally have the number “0”. Inincreasing sequential order, the subpixels are now copied into thestrips from the compressed source images until the next strip beginswith the subpixel numbers Kr_(SPStart)(1) and Kl_(SPStart)(1). Thefollowing numbers give the starting subpixels in the source images:Krq _(SPStart)(1)=int{(start−scpitch/4+i·scpitch)/spsize−SPJ} and  (19)Klq _(SPStart)(i)=int{(start+scpitch/4+i·scpitch)/spsize−SPJ}.  (21)

SPJ is a system-specific whole number which may be one or multiples ofthree and ensures that at the transition from one lens to the next, theright colour is selected. For SPJ=0, the counting takes place on theimage screen. FIG. 4 shows an example for SPJ=1 and FIG. 2 shows anexample for SPJ=9. The HR interlacing is also illustrated in FIG. 7.This drawing shows that on copying of the subpixels into the strips, thestarting subpixels in the source image start ever further forward thanwhere they were ended in the previous strip. This ensures thecontinuity.

This sequence of the copying procedure maintaining the subpixels ispreferably designated High Resolution Space Multiplexing.

(S6): A further high-resolution filtration, designated HR filtering or“HR sharp filtering” here, serves to improve resolution. Thedistribution of brightness and of colour is divided among differentpixels and the surroundings.

It is assumed that the original coloured source images from the rightand left viewing perspectives are available in the full resolution ofthe monitor used, e.g. 1600×1200 pixels. The novel property of thefiltration described below is that the brightness information in theimages is filtered quite differently from the colour information. Thepossible increase in resolution compared with previous colour imagerepresentations is thereby achieved that optimal adaptation to thevisual physiological perception properties takes place. The adjoiningarrangement of the subpixels on a TFT screen is thereby utilised. Thebasic idea is to distribute the brightness information over thesubpixels and to distribute the colour information over thesurroundings. By this means, the resolution for brightness can betripled in the horizontal direction, whilst more than ⅔ of theinformation is filtered out of the colour information. The differentperception by the human eye of brightness and colour is used by, amongother things, PAL coding in that with a relatively small additionalchannel, a high level of colour quality is achieved in televisionpictures. In the current autostereoscopic representation of colourimages, the horizontal direction of each partial image is magnifiedapproximately three times by the cylindrical lenses. This means that theoriginal information content of the brightness information can belargely retained during compression filtering. Thereby that onstereoscopic representation, a right and a left image exist, in endeffect the brightness information content is doubled compared with aconventional two-dimensional representation. By this means, a subjectivedoubling of the image quality is achieved with the invention describedhere, and with this 3-D photographic quality, the leap into athree-dimensional perception with a flat screen display is alsoachieved.

1. Brightness filtering. The original images are designatedP_(or)(f,i,k) and P_(ol)(f,i,k). k is the counter for the numbers, i forthe columns and f for the colours R, G, B and the brightnessY═(R+G+B)/3. In general, k runs from 0 to 1199, i from 0 to 1599 and ffrom 0 to 3. The first step is pixel-by-pixel filtering of thebrightness values Y to the subpixels in the compressed imageP_(HFr)(f,m,n). The filter has the coefficients H_(YF) (ν, μ). Thefilter properties will now be described in greater detail using twoexamples: one which only operates within one line and one whichencompasses the upper and lower lines. The first condition placed on thecoefficients is that a constant grey value in the original imagesupplies the same constant grey value in the target image. That means:the total over all the coefficients is one. $\begin{matrix}{{\sum\limits_{\mu,v}{H_{XF}( {\mu,v} )}} = 1} & (22)\end{matrix}$

The second condition is that a white pixel in the original imagesupplies in total a white image again—in the surroundings of the targetpixel. This leads to the following three conditions: $\begin{matrix}{{{\sum\limits_{{\mu = {- 3}},0,{+ 3}}{\sum\limits_{v = {- 1}}^{+ 1}{H_{YF}( {\mu,v} )}}} = \frac{1}{3}};} & (23) \\{{{\sum\limits_{{\mu = {- 2}},1}{\sum\limits_{v = {- 1}}^{+ 1}{H_{YF}( {\mu,v} )}}} = \frac{1}{3}};} & (24) \\{{\sum\limits_{{\mu = 1},2}{\sum\limits_{v = {- 1}}^{+ 1}{H_{YF}( {\mu;v} )}}} =} & (25)\end{matrix}$

The filtering operation may be described withf(m)=(m)mod(3)=m−3·int{m/3} and i(m)=int{m/3}, and $\begin{matrix}{{P_{HFr}( {{f(i)},{i(m)},n} )} = {\sum\limits_{\mu,v}{{H_{YF}( {\mu,v} )} \cdot {P_{or}( {3,{m - \mu},{n - v}} )}}}} & (26)\end{matrix}$

The following first number example describes a line operator whereby thefilter coefficients are zero for ν=+1,−1 TABLE 1 Filter coefficients fora HR line filter H_(YF(μ; v)) N M −3 −2 −1 0 1 2 3 O −1.5/9 1/9 2/9 6/92/9 1/9 −1.5/0

The next example illustrates a line-crossing filter operation: TABLE 2Filter coefficients for a line-crossing HR filter H_(YF(μ; v)) N M −3 −2−1 0 1 2 3 −1 −0.65/9 0.1/9 0.4/9 −0.5/9 0.4/9 0.1/9 −0.65/9 0  −1.2/90.8/9 1.2/9    9/9 1.2/9 0.8/9  −1.2/9 1 −0.65/9 0.1/9 0.4/9 −0.5/90.4/9 0.1 −0.65/9

This two-dimensional filter is designed such that the coefficientsdecrease in reciprocal proportion to the separation from the centre. Thedesign with H_(YF)(0,0)=1 is an extreme example, which comes into effectfor natural images if the original contrast range was previously reducedin order to be able to increase it again during HR filtering forsharpness elevation. For instance, the value range of the source images(0-255) could be compressed to 40 to 220. That is one method by whichthe achievable sharpness effect may additionally be weighed against acontrast effect.

This brightness-HR filtering provides a grey image on average. If,however, the permissible range between 0 and 255 is exceeded in thetarget image, then the range for visualising must be restricted again tothe permissible range. In the process, colour effects can arise, whichdepend upon the image content.

2. Colour filtering: in a second step, the colour information is nowadded again with a reduced local resolution. For this purpose, thecompressed image generated under (S1) in Equation (3) may be utilisedagain for right and left. $\begin{matrix}{{P_{S}( {f,i} )} = {\sum\limits_{\mu = {- 2}}^{+ 2}{{C_{TP}(\mu)} \cdot {{Po}( {f,{{3i} - \mu}} )}}}} & ( {27a} )\end{matrix}$

In this image, for right and left, the colour difference values aregenerated for the brightness value Y=(R+G+B)/3: DR=R—Y; DG=G−Y; DB=B−Y.This operation is set out in Equation (27): $\begin{matrix}{{P_{Sr}( {{f + 3},i,k} )} = {{P_{Sr}( {f,i,k} )} - {\sum\limits_{f = 0}^{3}{{P_{Sr}( {f,i,k} )} \cdot \frac{1}{3}}}}} & (27)\end{matrix}$

The same operation is undertaken for the left compressed image. Thedifference values are overlaid again—distributed over thesurroundings—on the HR-filtered grey image. This is carried out anew bymeans of one or two-dimensional low-pass filtering. As the low-passfilter, for instance, that in Equation (2) may be used again. This thenresults in the following operation, three times for f=0, 1, 2:$\begin{matrix}{{{P_{HRr}( {f,m,n} )}\text{:} = {P_{HRr}( {f,m,n} )}} + {\sum\limits_{\mu = {- 2}}^{2}{{C_{TP2}(\mu)} \cdot {P_{Fr}( {{f + 3},{m - \mu},n} )}}}} & (28)\end{matrix}$

Still more favourable would be a two-dimensional low-pass filterC_(TP)3(i,k), e.g. for i, k from −1 to 1, whereby the sum must againequal 1. The coefficient values could be the following in Table 3: TABLE3 Simple 2-dimensional low-pass filter for inserting the colours.C_(TP)(i, k) K I = −1 0 +2 −1 1/15 2/15 1/15 0 2/15 3/15 2/15 +1 1/152/15 1/15

The filtering would then become the following operation, which isnaturally somewhat more effort to carry out than a one-dimensionalversion. $\begin{matrix}{{{P_{HRr}( {f,m,n} )}\text{:} = {P_{HRr}( {f,m,n} )}} + {\sum\limits_{\mu,{v = {- 1}}}^{+ 1}{{C_{TP3}( {\mu,v} )} \cdot {P_{Sr}( {{f + 3},{m - \mu},{n - v}} )}}}} & (28)\end{matrix}$

The symbol “:=” stands for the programming-related designation forreplacement of the same variables on the right side by the result of theleft side.

The same operation should naturally be carried out for the left image.

At the end, the range limitation must still be carried out and thefloating point numbers must be rounded to whole numbers between 0 and255. Two steps are available for this. 1. A range that is possibly toolarge may be compressed; 2. Numbers below 0 and over 255 may be set to 0or 255.

To conclude the description of HR filtering, an alternative presentationof the colour pixels will now be mentioned, which is known as theh-c-perception model (hue, colour). This model also contains informationabout the colour saturation. The R, G, B pixel values may beunambiguously converted into h-c values as follows and also back again.h=√{square root over (R ² +G ² +B ²)}  (29)

The minimum white content is determined: w=min{R, G, B}, and from thedifference value DR=R−w, DG=G−w, DB=B−w, a colour angle which liesbetween 0 and 360 degrees is calculated.

Dependent upon which difference vanishes, the following apply:$\begin{matrix}\begin{matrix}{\Theta = {\frac{240^{i}}{\pi} \cdot {{atn}( \frac{DG}{DR} )}}} & {{DB} = 0} \\{\Theta = {{\frac{240^{{^\circ}}}{\pi} \cdot {{atn}( \frac{DR}{DB} )}} + {120{^\circ}}}} & {{DR} = 0} \\{\Theta = {{\frac{240^{{^\circ}}}{\pi} \cdot {{atn}( \frac{DR}{DB} )}} + {240{^\circ}}}} & {{DG} = 0}\end{matrix} & (30)\end{matrix}$

On use of the colour model, the intensity value h is HR-filtered as Ypreviously was, and subsequently the colour is added filtered with alow-pass filter.

On mounting the previously described lenticular raster screen 20 (FIG.2), it may arise that the separation of the raster screen 20 from thesurface of the image screen 1 is not precisely maintained. Such slightseparation deviations lead to slight colour Moiré faults in the images.If the separation is not precisely maintained, the visible subpixelstrips become somewhat smaller or larger, such that particular coloursare frequently repeated within an image strip. According to theinvention, therefore, the cylindrical lenses 22 a, 22 b (see also FIG.2) are, for instance, arranged angled to the vertical, such that theydistribute the colours evenly over the existing subpixels R, G and B andthe colour Moiré faults disappear.

In order to avoid colour faults, the cylindrical lenses 22 a, 22 b ofthe raster screen 20 according to FIG. 9 are arranged not vertically,but slightly inclined to the right or the left, whereby the inclinationis at an angle of between 0° and 45° (−45°) to the vertical direction(arrow v in FIG. 9). Naturally, the subpixel strips assigned to rightand left must then have the same inclination. In FIG. 9, for the sake ofclarity, only two right visible subpixels 61 a, 61 b and two leftvisible subpixel strips 62 a, 62 b are shown on the image screen 1.According to the invention, the inclination of these subpixel strips 61,62 is thereby achieved that of the subpixels which physically are stillvertically arranged, by means of software, those subpixels are switchedthat lie on the subpixel strip lying inclined in FIG. 9. Under minuteobservation, the subpixel strips 61, 62 lying inclined are thereforebordered on both sides by stepwise structured flanks of the individualsubpixels R, G and B. The invisible reserve subpixel strips lyingbetween these are similarly inclined.

The inclination of the cylindrical lenses 22 a, 22 b and of the subpixelstrips 61 and 62, expressed as the ratio of the vertical to thehorizontal image screen sections is, according to the invention,preferably in the range 6:1 to 3:1. FIG. 9 shows an example with aninclination/slope of 6:1. The right and left subpixel strips 61, 62,which are controlled in inclined manner, are each formed on average ofeight controlled subpixels, of which approximately four are visiblebehind the lenses.

With an inclined arrangement both of the cylindrical lenses 22 and acorrespondingly inclined control of the subpixels R, G, B which arefundamentally arranged vertically on the TFT image screen 1, in order toform inclined subpixel strips 61, 62, fine adjustment of the lenticularraster screen 20 to the TFT image screen 1 using test images that can bedefined in advance, is possible in software by correcting the subpixelcontrol. By this means, displacement of the controlled subpixel strip61, 62 in the horizontal and/or vertical direction is possible with theaccuracy of one subpixel R, G, B. The inclined position described, bothof the cylindrical lenses 22 and of the visible subpixel strips 61, 62leads, for the human eye, to a seemingly averaged-out colour fault inthe vertical direction. Since, however, due to the inclined arrangement,the colour Moiré faults are largely suppressed, a fine adjustment ofthis type, accurate to one subpixel, is tolerable with regard to anycolour faults. Therefore, the fine adjustment described is also moreadvantageous than inclination of the subpixel strips alone, which isalso possible, i.e. using vertically arranged lenses, since colour Moiréfaults can be further increased by this.

In the above embodiments, it has been taken as a precondition that thesubpixels are each controlled on the image screen 1 such that withoutuse of an eye tracker or similar, a 3-D representation is obtainedsubstantially only for one particular viewing direction. On the otherhand, FIG. 10 shows that the device according to the invention, withcorresponding use of the above method features and device features isalso simultaneously suitable for viewing a 3-D image from a plurality ofviewing directions, such that the same image may be seen by a pluralityof observers simultaneously and with the perspectives appropriate to therespective viewing direction. For this purpose, preferably large-scaleimage screens with, for instance, 12,000 or more pixels per line and,for instance, 2,400 lines are used in order that a sufficient number ofsubpixels is available for each perspective.

FIG. 10 shows, in exemplary manner, the ray path for a reproductionsystem of this type. As shown, for instance, in FIG. 4, a lenticularraster screen 64, of which only one cylindrical lens is shown, isdesigned and arranged in front of the image screen 1 such that from aposition I in front of the image screen 1, for instance, 3 subpixels R,G and B are seen with one eye, which form a subpixel strip or imagestrip delineated by the edge rays 65 and 66 drawn with solid lines. Thenext ca. 5 subpixels to the right in FIG. 10, however, are seen from aposition II, and the subpixel strips or image strips seen from there aredelineated by the dashed lines 67 and 68. From each further position IIIand IV, the subpixel strips or image strips visible from there eachstart, seen from the left, at a subpixel identified by a dotted line 69or a dot-dashed line 70. The arrow points of the lines 65 to 70 eachshow at which subpixel the respective subpixel strip begins. As alsoshown in FIG. 10, the subpixel strips may have different widths and endat the next respective arrow point. Alternatively, the subpixel stripsmay also have the same width throughout, as shown in FIG. 7.

The reproduction system according to FIG. 10 has the peculiarity, ascontrasted with FIG. 1, that not just two half images or perspectivesare allocated to the subpixels of the image screen 1 for a right andleft eye but, continuously, image strips that come from more than twoperspectives. In particular, the four subpixel strips beginning at thearrow tips 65, 67, 69 and 70 come from one and the same image sectionwhich, however, was recorded from different viewing directions.Therefore, subpixel strips 71 to 74 are allocated to one image strip inFIG. 10 one after the other, which are allocated to the perspectivesfrom the positions I to IV such that from each of the four positions, itis always only the associated subpixel strip or image strip or aparticular perspective that is visible. Following this (i.e. in FIG. 10,continuing towards the right), this sequence of viewing directionsrepeats for further image screen sections, whereby the associatedsubpixel strips are again controlled with signals from right to leftthat correspond to the associated views from the four viewing directionsI to IV, whereby the sequence of viewing directions I to IV is the sameeverywhere.

In order that for an arbitrary viewing direction, it is notoverwhelmingly subpixels of one colour that will be seen, as would bethe case, for instance, with the use and arrangement of the lenticularraster screen 33 according to FIG. 4, in similar manner to FIG. 9,suitably a plurality of overlapping subpixel lines are grouped togetherand controlled in inclined orientation. By this means, it is achievedthat from each viewing direction, all three colours R, G and B arealways seen, even if with each cylindrical lens only a single subpixelis visible per viewing direction and per line.

Finally, it may be provided that between the different subpixel strips,additional safety pixel strips are provided which, for instance, havethe width of one subpixel. This leads, for instance, in FIG. 10 theretothat of each subpixel strip, only a central section 75 is visible,whilst in each case, one subpixel strip lying to the right or the leftof it serves as an invisible safety strip 76 or 77. By this means, theproblem of overlapping of adjacent pixel strips that can arise due tothe inclined course of the subpixels and due to the simultaneous use ofone subpixel (e.g. 78 in FIG. 10) from two adjacent subpixel strips issolved.

Overall, therefore, a substantial difference in the embodiment accordingto FIG. 10 from the embodiments according to FIGS. 2 to 9 consistssolely therein that the separations between the image strips (=visualjumps 30, 31 in FIG. 3) belonging to one view or one perspective areused for the arrangement of a plurality of views. This plurality ofviews is always simultaneously available. If, therefore, the angularseparations between the different views is sufficiently large, the sameimage may be viewed by a plurality of persons simultaneously in 3-Dquality and from the designated perspectives.

The 3-D reproduction system described may be used, for instance, forreproducing images recorded with video cameras, in medical technologyfor computer tomography or for stereo endoscopy, in architecture foranimations of buildings and landscapes and in computer graphics forvirtual reality productions or in 3-D games. A further important area ofuse is “telepresence”. In dangerous areas or inaccessible places,remotely-controlled cameras and robots may now be put in place withoutthe natural impression of depth having to be sacrificed.

The invention is not restricted to the embodiments described, which canbe developed in manifold fashion. This applies in particular for thetypes of interlacing described by reference to the drawings, which weredescribed merely in exemplary manner and may be amended, in particularwith regard to the number of subpixels per subpixel strip or the numberof lenses or barriers distributed over the image screen width per rasterscreen. It is clear that there may also be cases whereby the imagepoints are formed not from three, but two, or more than three differentcoloured subpixels. The allocation of subpixels used for brightness andcolour control and their distribution to adjoining subpixels or thesurroundings and described in the context of high-resolution filtering(S6) may also be amended and adapted to particular needs. Furthermore,it is possible to use the same image screen entirely or partially forother purposes than those described. It would be possible, for instance,to design the barrier raster screens 41 or 42 such that the blackbarrier strips 45 or 46 may be switched on or off. By this means, thesame image screen could also be used by, on the one hand, switching offall barrier strips 45, 46, for normal two-dimensional representations.On the other hand, it is conceivable to use, for instance, one half ofthe image screen in the manner described, whilst the other half is usedfor two-dimensional representations by switching off the barrier strips45, 46. Finally, it should be understood that the various features andprocess steps (e.g. (S1) to (S6)) can also be used in other combinationsthan those shown and described.

1. Autostereoscopic reproduction system for 3-D representation,comprising a processor unit (3) for obtaining first and second imagestrip signals (10,11) for different viewing directions, an image screen(1) with image pixels arranged in lines and adjoining one another, whicheach have a predetermined number of subpixels (R, G, B) of differentcolours arranged side by side, a coding unit (6, 9) for interlacedcontrol of the subpixels (R, G, B) with the image strip signals (10,11)such that in each line of the image screen (1), in alternating manner,sequential first and second subpixel strips (25, 26; 35, 36; 49, 50; 61,62) generates respectively a first and a second image strip (28, 29; 37,38; 47, 48; 55, 56) for the viewing directions, and a raster screen (20,33, 41, 42) arranged in front of the image screen (1), which for adefined viewing region in front of the image screen (1) combines thefirst and second image strips (28, 29; 37, 38; 47, 48; 55, 56) to firstand second images, characterised in that the coding unit (6, 9) iscontrollable and the raster screen (20, 33, 41, 42) is dimensioned andarranged such that at least the first and second image strips (28, 29;37, 38; 47, 48; 55, 56, 71, 72) and possibly further image stripsgenerated in a selected region of the image screen (1) appear to one ormore observers to be overlap-free (disjoint) and a constant sequence ofthe colours of the subpixels (R, G, B) is obtained in the first (second)subpixel strip (25, 26; 35, 36; 49, 50; 61, 62).
 2. Reproduction systemaccording to claim 1, characterised in that the first (second) subpixelstrips (25, 26; 35, 36; 49, 50; 61, 62) are separated from each othersuch that the separations (30, 31) between lateral ends of a first(second) subpixel strip (25, 26; 35, 36; 49, 50; 61, 62) facing towardseach other from a first (second) subpixel strip (25, 26; 35, 36; 49, 50;61, 62) leading it and/or following it in the line direction correspondsto a whole number multiple of an image pixel or the width of a subpixel.3. Reproduction system according to claim 2, characterised in thatfurther subpixels (27) are arranged between the first and secondsubpixel strips (25, 26) assigned to the image strips (28, 29). 4.Reproduction system according to claim 1, characterised in that theraster screen (20) is mounted undisplaceable relative to the imagescreen (1).
 5. Reproduction system according to claim 4, characterisedin that the further subpixels (27) serve for spatial separation of thefirst and second subpixel strips (25, 26) and the raster screen (20) isdesigned and arranged such that the further subpixels (27) areinvisible.
 6. Reproduction system according to claim 4, characterised inthat the coding unit (6, 9) is set up to control the further subpixels(27).
 7. Reproduction system according to claim 6, characterised in thatthe raster screen (33) has a pitch separation which substantiallycorresponds to the width of two subpixels (R, G, B) and that thearrangement is undertaken such that the subpixels (R, G, B) in each lineare assigned in alternating manner to the first and second image andeach subpixel strip (35, 36) has the width of one subpixel (R, G, B). 8.Reproduction system according to claim 1, characterised in that theraster screen (20, 33) is a lenticular raster screen.
 9. Reproductionsystem according to claim 1, characterised in that the raster screen(41, 42) is a barrier raster screen.
 10. Reproduction system accordingto claim 9, characterised in that the barrier raster screen (41) hastransparent slits (43) with a width which substantially corresponds tothe width of three subpixels (R, G, B).
 11. Reproduction systemaccording to claim 1, characterised in that the processor unit (3)and/or the coding unit (6, 9) is assigned to a position detector (14)indicating the position of an observer in front of the image screen (1).12. Reproduction system according to claim 1, characterised in that theraster screen (20) is a lenticular raster screen with cylindrical lenses(22 a, 22 b) arranged at an angle to the vertical (v) of the imagescreen (1) and that the subpixels (R, G, B) on the image screen arecontrollable such that the visible first and second subpixel strips (61,62) have substantially the same inclination as the cylindrical lenses(22 a, 22 b).
 13. Reproduction system according to claim 12,characterised in that a fine horizontal adjustment of the lenticularraster screen (20) relative to the image screen (1) takes place by meansof a corresponding inclination of the visible subpixel strips (61, 62).14. Reproduction system according to claim 1, characterised in that thefirst and second images (4, 5) are compressed in the horizontaldirection before formation of the image strip signals (7, 8). 15.Reproduction system according to claim 14, characterised in that thesubpixel values of the first and second ith pixels of the compressedimages (7, 8) are copied in colour-true manner onto the subpixels of theith first and second strips of the image screen (1) in correspondence to(49) and (50), whereby the starting positions of the individual stripsare calculated adaptively, for instance, using the Equations (20) and(21), whereby a colour appearing twice in one image screen strip is alsorecorded twice.
 16. Reproduction system according to claim 1,characterised in that three dynamic words startr, startl and scpitch aredefined and on the display the kth first strip begins with the subpixelwhich corresponds to the whole number portion of the product(startr+k)*scpitch, named int{(startr+k)*scpitch}, and the second withthe subpixel that corresponds to the whole number portion of the product(startl+k)*scpitch.
 17. Reproduction system according to claim 1,characterised in that a constant horizontal compression factor stretch0(e.g. stretch0=0.33) is predetermined and the value scpitch is splitinto a whole-number constant portion sp0 and a dynamic portion scpitchv,where scpitch=sp0+scpitchv, that the subsequent subpixels of the firstcompressed image, sfr0+int{k*scpitchv} to sfr0+int{k*scpitchv}+spon0 arecopied into the first kth image screen strip in the same ascendingsequence, whereby sfr0 is chosen such that the colour of the firstsubpixel in the kth first strip corresponds to the colour of the firstsubpixel from the first compressed image sfr0+int(k*strechv) and thesize of spon0 is chosen such that the entire kth first strip is coveredon the image screen, and that a similar procedure is used for the secondstrip.
 18. Reproduction system according to claim 1, characterised inthat only the first three subpixels of a kth strip are copied in and theremainder of the kth first or second strip are set to black, i.e. to 0.19. Reproduction system according to claim 1, characterised in that thesubpixels spr0+int{startr+k*scpitch} to spr0+int{startl+k*scpitch}−1 ofthe first uncompressed image are copied into the kth strip incolour-true manner and into the kth second strip, the subpixelsspl0+int{startl+k*scpitch} to spl0+int{startr+(k+1)*scpitch}−1, wherebyspr0 and spl0 are chosen once for the whole image such that colour-truecopying is assured.
 20. Reproduction system according to claim 1,characterised in that a fourth word stretch is passed dynamically andthe first and second images generated in original size are compressed bythe factor stretch, then subsequently to be stretched in filteringmanner by a constant factor 1/stretch0 or the dynamic factor 1/stretch,and then to be copied dynamically and interlaced to the first and secondstrips of the image screen.
 21. Reproduction system according to claim1, characterised in that to each subpixel is assigned its own brightness(grey level) information (Y) in positionally faithful manner, whilst theassociated colour information is distributed in weighted manner to thecorresponding colour subpixels in the surroundings of the same subpixelstrip and possibly also to at least one adjoining subpixel strip of thesame perspective.
 22. Reproduction system according to claim 1,characterised in that first and second original images (4, 5) aregenerated or made available in full pixel resolution and from theseimages, HR-compressed images generated according to the system setting(S6), in which the brightness values Y═(R+G+B)/3 of the original imagesare filtered onto the subpixels by means of an HR filter HYF(i,k)according to Equation (26), whereby the sum of all the filtercoefficients is equal to 1 (Equation (22)), whilst the parts of thecoefficients operating on the same colours have the sum ⅓ (Equations(23, 24, 25)).
 23. Reproduction system according to claim 1,characterised in that first and second original images (4, 5) aregenerated or made available in full pixel resolution and from these,images compressed to ⅓ horizontally by means of a suitable deep-passCTP(i), (e.g. Equations (1, 2)) are created according to Equation (3),and that these are interlaced according to (S5) such that the subpixelsbelonging to the respective partial images are copied in unalteredsequence into the first and second strips, whereby the start pixels arefound according to Equations (20) or (21) using the given number SPJ.24. Reproduction system according to claim 1, characterised in thatfirst and second original images (4, 5) are generated or made availablein full pixel resolution and from these images, images horizontallycompressed to ⅓ by means of a suitable deep-pass CTP(i) (e.g. Equations(1, 2)) are created according to Equation (3), and that from thesecompressed images, the colour difference values DR=R−Y, DG=G−Y andDB=B−Y are formed, these are overlaid deep-pass filtered (e.g. accordingto Equations (28, 27)) on the HR-compressed images formed according toclaim 22 and interlaced as in claim 22 according to (S5). 25.Reproduction system according to claim 1, characterised in that firstand second images are generated or made available in original size andconventional resolution, although they do not exhaust the fullbrightness value range from 0 to 255, but a restricted value range, forinstance, between 30 and 240, which may also be achieved throughcontrast reduction, and that a grey base value is added to thecompressed and HR-filtered image (e.g. the value 30), such that onfiltration according to claim 22, negative brightness values fromnegative filter coefficients can also be taken into account, providedthey do not
 26. Reproduction system according to claim 1, characterisedin that subpixels of adjoining lines are also included in theHR-compression filtering according to claim 23 and the colour overlayingaccording to claim 24 as, for instance, Tables 2 and 3 show. 27.Reproduction system according to claim 1, characterised in that blackand white patterns or character fonts according to one of the abovemethods is made available in a compressed HR-format, stored and madeavailable for insertion.
 28. Reproduction system according to claim 1,characterised in that, from the dynamic parameters startr, startl andscpitch, the observer positions are reconstructed and the object scenesare automatically generated from the correspondingly adjusted camerapositions.
 29. Reproduction system according to claim 1, characterisedin that the dynamic position-adaptation may also be paused, stopped orswitched off and that the parameter scpitch may, among other things, beexactly twice as large as one colour subpixel.
 30. Reproduction systemaccording to claim 1, characterised in that first and second colourimages are generated or made available in original size and resolutionin R, G, B and h, w, c format (Equations (29, 30)), the w-portion(white) according to claims 19, 20 or 21 is HR-filtered and the twocolour values f1=c.cos(O) and f2=c.sin(O) occurring in the h-componentare respectively added to the associated colour subpixels in thesurroundings of the subpixel Sop, on which the subpixel filter operates,are filtered over a coefficient sum of 1, whereby the coefficientweights behave approximately reciprocally to the distance from thecentral subpixel Sop, whereby when the colour of the central subpixelSop occurs, a filter with the coefficient sum SKo=0 is used, whosecoefficient to the central subpixel Sop has the value 1, and the filteris controlled with the colour value c from the (h, w, c)-format. 31.Reproduction system according to claim 1, characterised in that, givensuitable HR-filtering, the resulting colour subpixel values arerestricted to the permissible range and to whole numbers as the colourvalue.
 32. Reproduction system according to claim 1, characterised inthat the first and second image strip signals, image strips and subpixelstrips are assigned to the right or left eye (23, 24) of an observer.33. Reproduction system according to claim 3, characterised in thatbetween the first and second subpixel strips, further subpixel stripsassigned to different viewing directions are present (FIG. 10), of whichfrom each viewing direction only two are visible for the right and lefteye of an observer.
 34. Reproduction system according to claim 33,characterised in that image signals belonging to the further subpixelstrips are permanently copied into the subpixel strips.
 35. Reproductionsystem according to claim 32, characterised in that the arrangement ismade such that for at least two observers, first and second image stripswith the associated perspectives, or at least four image strips with theassociated different perspectives are simultaneously visible.